The third episode of the current series of Inside No 9 pulled off a remarkable trick on the day of its transmission with the help of the Guardian.

The episode, The Riddle of the Sphinx, told the sinister story of cross and double cross and featured Steve Pemberton as a devious Cambridge Academic and crossword compiler known as Sphinx. As the programme panned out, successive answers were filled in on a giant crossword grid in his study.

Guardian crossword fans soon noticed that the answers in the programme were the same as the answers to the Guardian’s crossword that morning. Set by a new compiler called…Sphinx.

After the transmission all was revealed. The idea for the programme came from crossword obsessive Pemberton and the Guardian allowed him to compile their crossword.

Read more about how this all came about here.

Read a review here.

Inside No 9 is on Tuesdays on BBC2 at 10pm.